Bicycle hydraulic brake accentuate device

ABSTRACT

A bicycle hydraulic brake actuation device includes a hydraulic master cylinder housing having a bore, a master piston and a radial seal received in the bore a push rod and a lever. The push rod is configured to move the master piston and the radial seal between a neutral position and a braking position. The lever is pivotally attached to the housing for pivotal movement between an at rest position and a brake actuation position. The lever includes a contact surface configured and arranged to move the push rod as the lever is pivoted between the at rest position and the brake actuation position. Further, the push rod includes at least one roller configured to contact to the contact surface of the lever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to bicycle hydraulic brake actuationdevice. More specifically, the present invention relates to bicyclehydraulic brake actuation device that provides improved brakingcharacteristics in a braking system.

2. Background Information

Bicycling is becoming an increasingly more popular form of recreation aswell as a means of transportation. Moreover, bicycling has become a verypopular competitive sport for both amateurs and professionals. Whetherthe bicycle is used for recreation, transportation or competition, thebicycle industry is constantly improving the various components of thebicycle. One system that has been extensively redesigned is thehydraulic brake system.

The bicycle hydraulic brake system typically includes the hydraulicbrake actuation device, a rotor attached to one of the bicycle wheelsand a caliper adjacent to the rotor with brake pads that selectivelycontact the rotor in response to changes in hydraulic pressure in thehydraulic brake actuation device.

The hydraulic brake actuation device typically has a housing mounted thebicycle handlebar. The housing includes a bore, a master piston disposedin the bore and a lever arm pivotally supported on the housing. Pivotingmovement of the lever arm provides leverage for moving the master pistoncausing changes in the hydraulic pressure and movement of a slave pistonin the caliper. Typically, the brake pads are spaced apart from brakingsurfaces of the rotor until urged into braking contact with the rotor bymovement of the slave piston.

When the lever arm of the hydraulic brake actuation device is initiallymoved, braking contact is delayed because the brake pads must first moveand close the gap between the brake pads and the braking surfaces of therotor. The movement of the brake pads typically corresponds directlymovement of the lever arm in a movement ratio. Specifically, for eachangular degree of movement of the lever arm, there is a correspondingmovement of the brake pads.

It is desirable to have the brake pads move quickly toward the brakingsurfaces of the rotor in order to provide rapid braking response.However, in conventional hydraulic brake actuation devices, movement ofthe pads to the rotor requires an undesirable amount of lever armtravel.

In view of the above, it will be apparent to those skilled in the artfrom this disclosure that there exists a need for an improved hydraulicbrake actuation device that provides improved ratio of the movement ofthe brake pads relative to the movement of the lever arm. This inventionaddresses this need in the art as well as other needs, which will becomeapparent to those skilled in the art from this disclosure.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a hydraulic brakeactuation device with an improved master piston movement response.

Another object of the present invention is to provide push rod/rollerand lever configuration within a hydraulic brake actuation device thatimproves braking response.

Yet another object of the present invention is to provide a hydraulicbrake actuation device configured to respond to lever movement with afirst lever to piston movement ratio in a first portion of lever traveland a second lever to piston movement ratio in a second portion of levertravel.

The foregoing objects can basically be attained by providing a bicyclehydraulic brake actuation device with a hydraulic master cylinderhousing having a bore, a master piston and a radial seal received in thebore, a push rod and a lever. The push rod is configured to move themaster piston and the radial seal between a neutral position and abraking position. The lever is pivotally attached to the housing forpivotal movement between an at rest position and a brake actuationposition. The lever includes a contact surface configured and arrangedto move the push rod as the lever is pivoted between the at restposition and the brake actuation position. The push rod includes atleast one roller configured to contact to the contact surface of thelever.

These and other objects, features, aspects and advantages of the presentinvention will become apparent to those skilled in the art from thefollowing detailed description, which, taken in conjunction with theannexed drawings, discloses a preferred embodiment of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a side view of a bicycle that includes a hydraulic brakeactuation device in accordance with the present invention;

FIG. 2 is a schematic view of the hydraulic brake actuation deviceshowing the hydraulic brake actuation device operably connected to abrake caliper in accordance with a first embodiment of the presentinvention;

FIG. 3 is a side view of a portion of a front wheel of the bicycledepicted in FIG. 1 showing the brake caliper and a brake rotor inaccordance with a first embodiment of the present invention;

FIG. 4 is a perspective view of the hydraulic brake actuation deviceshown removed from the bicycle in accordance with the first embodimentof the present invention;

FIG. 5 is a perspective exploded view of the hydraulic brake actuationdevice in accordance with the first embodiment of the present invention;

FIG. 6 is a side elevational view of the hydraulic brake actuationdevice in accordance with the first embodiment of the present invention;

FIG. 7 is a cross-sectional view of the hydraulic brake actuation devicetaken along the line 7-7 in FIG. 6 showing details of a lever, a pushrod and a piston with the lever in an at rest position and the piston ina neutral position in accordance with the first embodiment of thepresent invention;

FIG. 8 is a cross-sectional view of the hydraulic brake actuation devicesimilar to FIG. 7, with the lever in a brake actuation position and thepiston in a braking position in accordance with the first embodiment ofthe present invention;

FIG. 9 is a cross-sectional view of the hydraulic brake actuation devicetaken along the line 9-9 in FIG. 6 showing a cam surface on the lever incontact with a roller of the push rod with the lever in the restposition and the piston in a neutral position in accordance with thefirst embodiment of the present invention;

FIG. 10 is a cross-sectional view of the hydraulic brake actuationdevice similar to FIG. 9, with the lever in a brake actuation positionand the piston in a braking position in accordance with the firstembodiment of the present invention;

FIG. 11 is a perspective exploded view similar to FIG. 5, showing ahydraulic brake actuation device in accordance with a second embodimentof the present invention;

FIG. 12 is a side elevational view of the hydraulic brake actuationdevice depicted in FIG. 11 in accordance with the second embodiment ofthe present invention;

FIG. 13 is a fragmentary side view of the hydraulic brake actuationdevice depicted in FIGS. 11 and 12 in accordance with the secondembodiment of the present invention;

FIG. 14 is a cross-sectional view of the hydraulic brake actuationdevice taken along the line 14-14 in FIG. 12 showing details of a lever,a push rod and a piston with the lever in an at rest position and thepiston in a neutral position in accordance with the second embodiment ofthe present invention;

FIG. 15 is a cross-sectional view of the hydraulic brake actuationdevice taken along the line 15-15 in FIG. 12 showing a cam surface onthe lever in contact with a roller of the push rod with the lever in therest position and the piston in a neutral position in accordance withthe second embodiment of the present invention;

FIG. 16 is a cross-sectional view of the hydraulic brake actuationdevice similar to FIG. 15, with the lever in a brake actuation positionand the piston in a braking position in accordance with the secondembodiment of the present invention;

FIG. 17 is a perspective view of the lever and the push rod of thehydraulic brake actuation device showing a pair of cam surfaces of thelever in contact with a pair of rollers of the push rod in accordancewith the second embodiment of the present invention;

FIG. 18 is a perspective view of a lever and a push rod of a hydraulicbrake actuation device showing a single cam surface of a lever incontact with a single roller of a push rod in accordance with a thirdembodiment of the present invention; and

FIG. 19 is a table showing movement of the piston (piston stroke), theratio of lever movement to piston movement and the braking force output.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Selected embodiments of the present invention will now be explained withreference to the drawings. It will be apparent to those skilled in theart from this disclosure that the following descriptions of theembodiments of the present invention are provided for illustration onlyand not for the purpose of limiting the invention as defined by theappended claims and their equivalents.

Referring initially to FIG. 1, a bicycle 10 is illustrated in accordancewith a first embodiment of the present invention. Among other things,the bicycle 10 includes a frame 12, a front fork 14, a front wheel 16, arear wheel 18, a handlebar 20 and a hydraulic braking system 22. Thefront fork 14 is pivotally supported on the frame 12. The front wheel 16is rotatably supported on the front fork 14 and the rear wheel 18 isrotatably supported on a rear portion of the frame 12 in a conventionalmanner.

The description below of the hydraulic braking system 22 is directed toa braking system configured for applying a braking force to the frontwheel 16. However, it should be understood that from the drawings andthe description herein that the bicycle 10 includes a separate brakingsystem configured for applying a braking force to the rear wheel 18.Since front and rear bicycle brake systems have the same components andoperate in the same manner, only the hydraulic brake system 22 installedfor applying a braking force to the front wheel 16 is described hereinfor the sake of brevity. Specifically, the description herein of thehydraulic braking system 22 applies to both front and rear brakingsystems.

As shown in FIG. 2, the hydraulic braking system 22 basically includes arotor 24, a brake caliper 26, a hydraulic line 28 and a hydraulic brakeactuation device 30. The brake caliper 26 is a slave cylinder and thehydraulic brake actuation device 30 is a master cylinder in thehydraulic braking system 22. As shown in FIG. 3, the rotor 24 isattached to the front wheel 16. The brake caliper 26 is fixed to thefront fork 14 adjacent to the rotor 24 in a conventional manner.

Referring again to FIG. 2, the brake caliper 26 includes a slave pistonS and brake pads P. The hydraulic line 28 is connected to both the brakecaliper 26 and the hydraulic brake actuation device 30 such thatincreases in fluid pressure within the hydraulic brake actuation device30 directed to the brake caliper 26 cause the slave piston S to move,thereby moving the brake pads P into contact with the rotor 24 andapplying a braking force the front wheel 16. As also shown in FIG. 2,the hydraulic brake actuation device 30 is secured to the handlebar 20.

With specific reference to FIGS. 4-10, a detailed description of thehydraulic brake actuation device 30 in accordance with the presentinvention is now provided.

As best shown in FIG. 5, the hydraulic brake actuation device 30basically includes a hydraulic master cylinder housing 34, a piston 36,a movement restricting portion 40, a push rod 44 and a lever assembly48.

As best shown in FIGS. 7 and 8, the hydraulic master cylinder housing 34basically includes a handlebar attachment portion 50, a hydraulic lineattachment end 62, a cylinder bore 64, a recess 66, a lever supportingportion 68 and a push rod supporting end 70. As best shown in FIG. 4,the hydraulic master cylinder housing 34 also includes a brake fluidreservoir 72.

Returning again to FIGS. 7 and 8, the hydraulic line attachment end 62is dimensioned to connect to the hydraulic line 28 in a conventionalmanner. As shown in FIGS. 9 and 10, the cylinder bore 64 defines an axisA and is dimensioned to receive the piston 36 such that the piston 36slides within the cylinder bore 64 along the axis A. The recess 66 isdimensioned to receive the push rod 44 such that the push rod 44 canmove within the recess 66 contacting a portion of the piston 36 as isdescribed in greater detail below.

As best shown in FIG. 5, the lever supporting portion 68 is defined bytwo spaced apart side walls 74. The two side walls 74 are each formedwith a bore 76. A pivot pin 78 is fitted into the bores 76 pivotallysupporting the lever assembly 48 in a manner described in greater detailbelow. As shown in FIGS. 7-10, the push rod supporting end 70 of thehydraulic master cylinder housing 34 includes a threaded aperture 80.

With specific reference to FIGS. 5 and 7-10, a detailed description ofthe piston 36 is now described. The piston 36 serves as a master pistonfor the hydraulic braking system 22. Movement of the piston 36 (a masterpiston) causes corresponding movement of the slave piston S in the brakecaliper 26 in accordance with corresponding increases in the fluidpressure within the hydraulic master cylinder housing 34.

The piston 36 is basically a cylindrically shaped member that basicallyincludes seal receiving recesses 82 and 84 fitted with seals 86 and 88and a push rod receiving end 90. The seals 86 and 88 are radial sealsthat extend around the outer circumference of the recesses 82 and 84.The seals 86 and 88 create a fluid seal between the cylinder bore 64 andthe piston 36. The push rod receiving end 90 includes a concavedsurface.

The piston 36 and the seals 86 and 88 are configured to move between aneutral position shown in FIGS. 7 and 9 and a braking position shown inFIGS. 8 and 10. The piston 36 serving as the master piston is biasedinto the neutral position (FIGS. 7 and 9) by a return spring 91 (FIGS. 7and 8) that is also disposed within the cylinder bore 64.

As shown in FIGS. 5 and 7-10, the movement restricting portion 40includes a first plate 92, a second plate 93, a bushing 94 and a bolt B.The first plate 92 is formed with a recess dimensioned to receive thebushing 94. The bushing 94 includes a central opening that has an innerannular surface (see FIGS. 9 and 10) that defines a push rod guidesurface 95, as described in greater detail below with the description ofthe push rod 44. The first plate 92 and second plate 93 include alignedapertures that receive the bolt B, such that the bolt B attaches themovement restricting portion 40 to the push rod supporting end 70 of thehydraulic master cylinder housing 34. Specifically, the bolt B threadsinto the threaded aperture 80. With the movement restricting portion 40installed on the push rod supporting end 70 of the hydraulic mastercylinder housing 34, the push rod guide surface 95 is preferably alignedwith the cylinder bore 64 and with the direction of movement of thepiston 36.

With specific reference to FIGS. 5 and 7-10, a description of the pushrod 44 is now provided. The push rod 44 is configured to move the piston36 and the seals 86 and 88 to the braking position (FIGS. 8 and 10) inorder to increase fluid pressure within the cylinder bore 64 causing theslave piston S in the brake caliper 26 to move the braking pads P toexert a braking force on the rotor 24.

As best shown in FIG. 5, the push rod 44 basically includes a pistoncontact portion 96, a lever contact portion 97 and a guided portion 98,with the lever contact portion 97 being disposed between the contactportion 96 and the guided portion 98. The piston contact portion 96includes a cap 100 that is preferably made of a friction reducingmaterial has an opening shaped to fit onto the piston contact portion 96and a master piston contact end that conforms to the concaved surfacethe push rod receiving end 90 of the piston 36.

The lever contact portion 97 is located in a longitudinal centralportion of the push rod 44 and includes opposing shafts 102 that extendfrom opposite sides of the lever contact portion 97. The lever contactportion 97 further includes a pair of rollers 104, one roller 104 beinginstalled on each of the shafts 102. The rollers 104 are spaced apartfrom one another on opposite sides of the lever contact portion 97.Consequently, the rollers 104 are supported for rotational movement atthe longitudinal central portion of the push rod 44. The outercircumferential surface of the rollers 104 define a cam surfacecontacting portion, as described in greater detail below.

The rollers 104 can be made of metal, nylon or a friction reducingmaterial. The rollers 104 can be rotatable sleeves as shown or caninclude internal bearings that contact the shafts 102 to provide smoothrolling about the shafts 102. The rollers 104 are cam rollers that aresupported for rotational movement on the shafts 102 as described ingreater detail below.

The guide portion 98 of the push rod 44 is basically an elongated rod orshaft that contacts the push rod guide surface 95. Specifically, theguide portion 98 extends through the bushing 94 such that the annularshape of the push rod guide surface 95 encircles a section of the guideportion 98 of the push rod 44. Consequently, the push rod 44 is confinedbetween the push rod guide surface 95 and the piston 36. Further, sincethe push rod 44 is so confined, the push rod 44 is restricted to linearmovement in coaxial alignment with the axis A of the cylinder bore 64corresponding to the direction of movement of the piston 36. As such,the hydraulic master cylinder housing 34 therefore includes the movementrestricting portion 40 that receives a portion of the push rod 44. Themovement restricting portion 40 is configured to limit the push rod 44to linear movement.

With reference to FIGS. 5, 7 and 8, a description of the lever assembly48 is now provided. The lever assembly 48 is pivotally attached to thehydraulic master cylinder housing 34 for pivotal movement about thepivot pin 78 between an at rest position shown in FIG. 7 and a brakeactuation position shown in FIG. 8. The lever assembly 48 basicallyincludes a lever member 110, a block member 112 and a reach adjustmentmechanism 114. The lever member 110 includes a grip end 118 and a pairof generally parallel extensions 120 extending from the grip end 118.Each of the extensions 120 is formed with an aperture 122 at a pivot endthereof, with the apertures 122 being coaxially aligned. Each of theextensions 120 is further formed with an elongated opening 124 which isa part of the reach adjustment mechanism 114.

The block member 112 includes a cam surface that is defined on a pair ofcam protrusions 128. Each cam protrusion 128 has a cam surface area 130.The two cam surface areas 130 define the cam surface of the block member112. The block member 112 also includes an aperture 132 about which theblock member 112 pivots, and an elongated slot 134 that is part of thereach adjustment mechanism 114.

The lever assembly 48 is pivotally supported on the lever supportingportion 68 of the hydraulic master cylinder housing 34 by the pivot pin78. Specifically, bushings 136 are installed in each of the apertures122 of the lever member 110 and in the aperture 132 of the block member112. With the block member 112 inserted between the extensions 120 ofthe lever member 110 and the aperture 132 aligned with the apertures122, the lever assembly 48 is inserted between the two spaced apart sidewalls 74 of the lever supporting portion 68. With the apertures 112 and132 and the bores 76 in the side walls 74 aligned, the pivot pin 78 isfitted into the apertures 112 and 132 and the bores 76 thereby pivotallysupporting the lever assembly 48 on the hydraulic master cylinderhousing 34.

The reach adjustment mechanism 114 basically includes a bolt 140, nuts142 and a pin 144. The pin 144 is inserted into the elongated slot 134and elongated opening 124 and the bolt 140 is inserted into holes formedin the block member 144 and through a threaded hole formed in the pin144. The reach adjustment mechanism 114 provides a reach adjustmentfeature to adjust the at rest position of the lever member 110.

As is shown in FIGS. 9 and 10, the cam surface areas 130 (contactsurface) are configured and arranged to move the push rod 44 as thelever assembly 48 is pivoted between the at rest position (FIG. 9) andthe brake actuation position (FIG. 10). As should be clear from thedrawings, the cam surface areas 130 are spaced apart in order to extendto opposite sides of the push rod 44 and contact the rollers 104 (thecam surface contacting portion). The cam surface areas 130 are generallyplanar, however it should be understood from the drawings and thedescription herein that the cam surfaces can alternatively have a curvedor arcuate contour.

As can be clearly seen in FIG. 9, the rollers 104 contact the camsurface areas 130 at a point G. In FIG. 10, the rollers 104 contact thecam surface areas 130 at a point H. The point G is farther away from thepivot pin 78 than the point H. A simple kinematics analysis of themovement of the lever assembly 48 verses the movement of the piston 36(and the push rod 44) shows that there are at least two different leverratios defined by their respective movements.

A first lever ratio is defined as a linear movement distance of thepiston 36 relative to an angular movement distance of the lever assembly48 with the lever assembly 48 proximate the at rest position (forexample, with rollers 104 in contact with the cam surface areas 130 inthe vicinity of the point G) and the piston 36 proximate the neutralposition (FIG. 9).

A second lever ratio is defined as a linear movement distance of thepiston 36 relative to an angular movement distance of the lever assembly48 with the lever assembly 48 proximate the brake actuation position(for example, with rollers 104 in contact with the cam surface areas 130in the vicinity of the point H) and the piston 36 proximate the brakingposition (FIG. 10). The first lever ratio is different from the secondlever ratio. Specifically, the first lever ratio is greater than thesecond lever ratio.

The chart in FIG. 19 shows data corresponding to the first and secondlever ratios with the left hand portion of the chart between the LeverStroke (mm) distances of about 1-6 mm corresponding approximately to theconditions defining the first lever ratio and the left hand side of thechart beginning at Lever Stroke (mm) distances of greater than about 7mm corresponding to the second lever ratio which is greater than thefirst lever ratio.

Second Embodiment

Referring now to FIGS. 11-17, a hydraulic brake actuation device 230 ofa hydraulic braking system in accordance with a second embodiment willnow be explained. In view of the similarity between the first and secondembodiments, the parts of the second embodiment that are identical tothe parts of the first embodiment will be given the same referencenumerals as the parts of the first embodiment. Moreover, thedescriptions of the parts of the second embodiment that are identical tothe parts of the first embodiment may be omitted for the sake ofbrevity.

As shown in FIG. 11, the hydraulic brake actuation device 230 has manyfeatures identical to the first embodiment. For instance, the hydraulicbrake actuation device 230 includes the piston 36 but does not includethe movement restricting portion 40 of the first embodiment. Thehydraulic brake actuation device 230 does include a hydraulic mastercylinder housing 234, a push rod 244 and a lever assembly 248 thatinclude modification when compared to their counterparts in the firstembodiment.

The hydraulic master cylinder housing 234 has many features that areidentical to those of the hydraulic master cylinder housing 34 of thefirst embodiment, except the side walls 74 and the push rod supportingend 70 of the first embodiment have been modified. Specifically, thehydraulic master cylinder housing 234 includes side walls 274 thatinclude slots 250 forming part of a movement restricting portion.Further, the threaded aperture 80 of the push rod supporting end 70 ofthe hydraulic master cylinder housing 34 of the first embodiment hasbeen eliminated. Otherwise, the master cylinder housing 234 has the samefeatures as the master cylinder housing 34 of the first embodiment.

The push rod 244 basically includes a piston contact portion 252 and alever contact portion 254. The piston contact portion 252 has a hollowinterior and a master piston contact end that conforms to the concavedsurface the push rod receiving end 90 of the piston 36. The levercontact portion 254 includes a pair of shafts 256 that extend fromopposite sides of the lever contact portion 254 and a central threadedaperture 260. A pair of rollers 262 are disposed on the shafts 256. Eachroller 262 includes a first roller area 264, a second roller area 266and an annular protrusion 268 extending therebetween. The rollers 262are configured such that the first roller areas 264 serve as cam surfacecontact portions, the second roller areas 266 extend into the slots 250.The annular protrusion 268 contacts an inner surface of the side walls274 to guide the push rod 244 thereby preventing side to side movementof the push rod 244.

Specifically, the second roller areas 266 and the slots 250 define amovement restricting portion and a push rod supporting end thatrestricts the push rod 244 to linear movement within the hydraulicmaster cylinder housing 234. The second roller areas 266 and the slots250 further serve as a guide portion of the push rod 244.

An adjuster bolt 270 is installed into the central threaded aperture 260of the lever contact portion 254 of the push rod 244. The adjuster bolt270 is dimensioned such that a portion of the adjuster bolt 270 extendsthrough the central threaded aperture 260. An exposed portion of theadjuster bolt 270 extends into the hollow interior of the piston contactportion 252 as shown in FIG. 14 and provides a positioning adjustmentbetween the push rod 244 and piston 36.

As shown in FIGS. 15 and 16, the lever assembly 248 is pivotallyattached to the hydraulic master cylinder housing 234 by the pivot pin78 for pivotal movement between an at rest position shown in FIG. 15 anda brake actuation position shown in FIG. 16. As shown more clearly inFIG. 11, the lever assembly 248 basically includes a lever member 310, ablock member 312 and the reach adjustment mechanism 114. The levermember 310 includes the grip end 118 and a pair of generally parallelextensions 320 extending from the grip end 118. Each of the extensions320 are similar to the extensions 120 of the first embodiment, but havebeen modified to include an offset 324. Offsets 324 are formed with theapertures 122.

With reference again to FIGS. 15 and 16, the block member 312 includes acam surface that is defined on a pair of cam protrusions 328. Each camprotrusion 328 has a cam surface area 330. The two cam surface areas 330define the cam surface of the block member 312. As shown more clearly inFIG. 11, the block member 312 also includes an aperture 332 and theelongated slot 134 which is part of the reach adjustment mechanism 114.

The lever assembly 248 is pivotally supported on the hydraulic mastercylinder housing 234 by the pivot pin 78. Specifically, bushings 136 areinstalled in each of the apertures 122 of the lever member 310 and inthe aperture 332 of the block member 312. Further, the pivot pin 78 isinserted into the bores 76, the aperture 332 and the apertures 122 tosupport the lever assembly 248 on the hydraulic master cylinder housing234.

As is shown in FIGS. 15 and 16, the cam surface areas 330 (contactsurface) are configured and arranged to move the push rod 244 as thelever assembly 248 is pivoted between the at rest position (FIG. 15) andthe brake actuation position (FIG. 16). As should be clear from thedrawings, the cam surface areas 330 are spaced apart in order to extendto opposite sides of the push rod 244 and contact the second rollerareas 266 of the rollers 262. It should be noted that the cam surfaceareas 330 are contoured or arcuate in shape thereby further enhancingthe first and lever ratios defined above with respect to the firstembodiment.

Third Embodiment

Referring now to FIG. 18, a hydraulic brake actuation device 430 of ahydraulic braking system in accordance with a third embodiment will nowbe explained. In view of the similarity between the first and thirdembodiments, the parts of the third embodiment that are identical to theparts of the first embodiment will be given the same reference numeralsas the parts of the first embodiment. Moreover, the descriptions of theparts of the third embodiment that are identical to the parts of thefirst embodiment may be omitted for the sake of brevity.

The hydraulic brake actuation device 430 is identical to the hydraulicbrake actuation device 30 of the first embodiment except that the blockmember 112 has been replaced with a block member 435 and the push rod 44has been replaced with a push rod 440. The block member 435 includesonly a single cam surface area 445. The push rod 440 includes a camsurface contacting portion 445 that includes first and second supportwalls 450 with a single roller 455 rotatably supported therebetween, theroller being configured to contact the cam surface area 445.

General Interpretation of Terms

In understanding the scope of the present invention, the term“configured” as used herein to describe a component, section or part ofa device includes hardware and/or software that is constructed and/orprogrammed to carry out the desired function. In understanding the scopeof the present invention, the term “comprising” and its derivatives, asused herein, are intended to be open ended terms that specify thepresence of the stated features, elements, components, groups, integers,and/or steps, but do not exclude the presence of other unstatedfeatures, elements, components, groups, integers and/or steps. Theforegoing also applies to words having similar meanings such as theterms, “including”, “having” and their derivatives. Also, the terms“part,” “section,” “portion,” “member” or “element” when used in thesingular can have the dual meaning of a single part or a plurality ofparts. As used herein to describe the present invention, the followingdirectional terms “forward, rearward, above, downward, vertical,horizontal, below and transverse” as well as any other similardirectional terms refer to those directions of a bicycle equipped withthe present invention. Accordingly, these terms, as utilized to describethe present invention should be interpreted relative to a bicycleequipped with the present invention as used in the normal ridingposition. Finally, terms of degree such as “substantially”, “about” and“approximately” as used herein mean a reasonable amount of deviation ofthe modified term such that the end result is not significantly changed.For example, these terms can be construed as including a deviation of atleast ±5% of the modified term if this deviation would not negate themeaning of the word it modifies.

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. Furthermore, the foregoing descriptions of theembodiments according to the present invention are provided forillustration only, and not for the purpose of limiting the invention asdefined by the appended claims and their equivalents.

1. A bicycle hydraulic brake actuation device comprising: a hydraulic master cylinder housing having a bore; a master piston and a radial seal received in the bore; a push rod configured to move the master piston and the radial seal between a neutral position and a braking position; a lever pivotally attached to the housing for pivotal movement about a lever pivot axis between an at rest position and a brake actuation position, the lever including a contact surface configured and arranged to move the push rod as the lever is pivoted between the at rest position and the brake actuation position, the push rod including at least one roller slidably contacting the contact surface of the lever to move from a first contact point to a second contact point as the lever is pivoted from the at rest position to the brake actuation position, respectively, with the second contact point being closer to the lever pivot axis than the first contact point.
 2. The bicycle hydraulic brake actuation device as set forth in claim 1, wherein the contact surface includes at least one cam surface area configured to contact to the roller.
 3. The bicycle hydraulic brake actuation device as set forth in claim 1, wherein the at least one roller is supported for rotational movement at a longitudinal central portion of the push rod.
 4. The bicycle hydraulic brake actuation device as set forth in claim 1, wherein the push rod is retained in a portion of the hydraulic master cylinder housing for linear movement along an axis generally aligned with the bore.
 5. The bicycle hydraulic brake actuation device as set forth in claim 1, wherein the hydraulic master cylinder housing includes a movement restricting portion that receives a portion of the push rod, the movement restricting portion being configured to limit the push rod to linear movement in response to contact by the cam surface.
 6. The bicycle hydraulic brake actuation device as set forth in claim 1, wherein the push rod is an elongated member having a master piston contact end and a contacting portion that is configured to contact the contact surface.
 7. The bicycle hydraulic brake actuation device as set forth in claim 6, wherein the contacting portion of the push rod includes first and second support walls with the roller rotatably supported therebetween.
 8. A bicycle hydraulic brake actuation device comprising: a hydraulic master cylinder housing having a bore; a master piston and a radial seal received in the bore; a push rod configured to move the master piston and the radial seal between a neutral position and a braking position; a lever pivotally attached to the housing for pivotal movement between an at rest position and a brake actuation position, the lever including a contact surface with spaced apart first and second cam surface areas configured and arranged to move the push rod as the lever is pivoted between the at rest position and the brake actuation position, and the push rod including a first roller and a second roller spaced apart from the first roller, the first cam surface area being configured to contact the least first roller and the second roller being configured to contact the second surface area.
 9. The bicycle hydraulic brake actuation device as set forth in claim 8, wherein the first roller and the second roller are rotatably supported on opposite sides of the push rod, and the first and second cam surface areas are configured to extend to the opposite sides of the push rod.
 10. A bicycle hydraulic brake actuation device comprising: a hydraulic master cylinder housing having a bore; a master piston and a radial seal received in the bore; a push rod formed as an elongated member having a contacting portion and a master piston contact end configured to move the master piston and the radial seal between a neutral position and a braking position and a contacting portion; a lever pivotally attached to the housing for pivotal movement between an at rest position and a brake actuation position, the lever including a contact surface with spaced apart first and second cam surface areas configured and arranged to contact the contacting portion of the push rod to move the push rod as the lever is pivoted between the at rest position and the brake actuation position, and the contacting portion of the push rod including first and second roller supporting parts on opposite sides thereof, with first and second rollers supported on respective ones of the first and second roller supporting parts, the first and second rollers being configured to contact respective ones of the first and second cam areas of the contact surface.
 11. The bicycle hydraulic brake actuation device comprising: a hydraulic master cylinder housing having a bore; a master piston and a radial seal received in the bore; a push rod configured to move the master piston and the radial seal between a neutral position and a braking position, the push rod including at least one roller; and a lever pivotally attached to the housing for pivotal movement between an at rest position and a brake actuation position, the lever including a contact surface configured and arranged to contact the at least one roller to move the push rod as the lever is pivoted between the at rest position and the brake actuation position, a first lever ratio being defined as a linear movement distance of the master piston relative to an angular movement distance of the lever with the lever proximate the at rest position and the master piston proximate the neutral position, and a second lever ratio being defined as a linear movement distance of the master piston relative to an angular movement distance of the lever with the lever proximate being the brake actuation position and the master piston being proximate the braking position, the first lever ratio being different from the second lever ratio.
 12. The bicycle hydraulic brake actuation device as set forth in claim 11, wherein the first lever ratio is greater than the second lever ratio. 